do you drive with both feet as my x did she burned up brakes so bad that the rotors turned blue and cracked . it`s that or you have bad bake lines or calipers like hank 85713 said the flexible rubber brake lines are known to pass pressure but not let back flow when they look good on the out side. or you are running to fast on long down hill. Say what u want about old truckers but loose control one time and we can all learn a lesson if we survive. campers are built on truck frames and should be driven as such . Slow down use your gears to help and be safe please .